Compelled Duel

Green rarely gets to script the combat step, and this is one of the tools that lets it try: cast on your main phase, it hands an attacker a fixed +3/+3 and forces the defending player to block that creature if they can. The lure clause is the design idea worth chewing on. You do not choose which creature does the blocking (the defender still picks from their eligible blockers), but you guarantee that something has to step in front of the body you just inflated. That is what turns the pump into more than survival insurance: the enlarged attacker makes the forced block a losing trade, or drags a creature the defender wanted to hold back into a fight it cannot win. This is green's fight idiom relocated into combat proper, where first strike, deathtouch, and any responding trick still get to speak, rather than resolving as a bare exchange of damage outside of blocks. The tension lives in what the +3/+3 buys against what it costs you: three points is often enough to survive the block and pick off whatever the defender was compelled to commit, but the defender may throw multiple blockers at the body, and the damage stops dead at those blockers unless you supply trample from elsewhere, so the forced fight rarely punches through. A two-mana line that reads as a plain trick but plays as a small puzzle about where you want the collision to happen and who gets stuck paying for it.